Coating processes – Immersion or partial immersion – Chemical compound reducing agent utilized
Reexamination Certificate
2001-03-22
2003-04-29
Lamb, Brenda A. (Department: 1734)
Coating processes
Immersion or partial immersion
Chemical compound reducing agent utilized
C118S069000, C427S398100
Reexamination Certificate
active
06555178
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process and an apparatus for nickel plating of an object such as electronic parts as well as a nickel-plated product produced by the apparatus according to the process. Particularly, the present invention relates to a technique for electrolessly plating a Ni—B layer on the surface of a substrate and then a Ni—P layer thereon.
2. Description of the Prior Art
One example of such nickel plating processes is disclosed in Japanese Patent Application Laid-Open No. 8-281957. This process involves laminating electrolessly deposited Ni—B and Ni—P layers, thereby intending to provide a nickel film which is free of membrane stress.
In this process, a pattern is formed on a ceramic substrate which is then subjected to a pretreatment by sensitizing-activation process. Next, a mask such as a resist may be stripped from the substrate which is then subjected to electroless Ni—P plating. The plating solution may comprises nickel salt (0.05-0.15 mo/l), a complexing agent, tartrate or glycin (0.075-0.225 mol/l), and a reducing agent, dimethylamine borane (0.5-4 g/l). The Ni—B plating solution further contains sodium hydrate for adjusting the pH condition of the solution within the range of 5.0-7.0. The ceramic substrate is immersed the Ni—B plating solution which has been heated to 50° C. for 20 minutes for plating
Thereafter, the plated substrate is washed with pure water and subjected to electroless Ni—P plating. The Ni—P plating solution comprises nickel salt (0.05-0.15 mo/l), a completing agent, tartrate or glycin (0.075-0.225 mol/l), and a reducing agent, sodium hypophosphite (10-30 g/l). The Ni—P plating solution further contains sodium hydrate for adjusting the pH condition of the solution within the range of 5.0-7.0. The ceramic substrate is immersed in the Ni—P plating solution has been heated to 50° C. for 50 minutes to obtain a nickel layer having a thickness of about 2 &mgr;m formed on the substrate.
These conventional electroless plating processes, however, often resulted in a ceramic substrate having a thinner portions present in some areas where Ni—P has not been deposited, particularly when the substrate to be plated has a large surface or when a large number of substrates are plated at one time. This thin portions may cause quality variations among the resulting products and thus cannot provide unstressing effect as described in the Japanese Patent Application Laid-Open No. 8-281957, just partially improvement of corrosion resistance by Ni—P layer.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a process for nickel plating which comprises the steps of electrolessly forming a Ni—B layer on a substrate and then a uniform and even Ni—P layer on the Ni—B layer.
Another object of the present invention is to maintain the concentration of the Ni—B plating solution deposited on the substrate in the above-described process.
These and further objects of the present invention are achieved by the novel process and apparatus for nickel-plating as well as nickel-plated product of the present invention.
One aspect of the present invention provides a nickel plating process which comprises the steps of: electrolessly plating a Ni—B layer on a substrate and then a Ni—P layer on the Ni—B plated substrate to obtain a substrate having a Ni—B layer formed on the surface thereof and a Ni—P layer superimposed on the Ni—B layer formed on the substrate. In this process, the substrate is subjected to drying-protection treatment after the Ni—B plating step and before the Ni—P plating step. In this way, a uniform and even Ni—P layer can be electrolessly plated on the electrolessly deposited Ni—B layer.
Another aspect of the present invention provides a nickel plating apparatus which comprises: a Ni—B plating bath containing a Ni—B plating solution in which a substrate is immersed for electroless Ni—B deposition; a Ni—P plating bath containing a Ni—P plating solution in which the substrate having the Ni—B layer formed thereon is immersed for electroless Ni—P deposition; and a transporting member for transporting the substrate from the Ni—B plating bath to the Ni—P plating bath; wherein the Ni—B layer formed on the substrate is prevented from drying during the transportation of the substrate from the Ni—B plating bath to the Ni—P plating bath. In this way, a uniform and even Ni—P layer can be electrolessly plated on the electrolessly deposited Ni—B layer.
Another aspect of the present invention provides a nickel plated product produced in the nickel plating apparatus according to the nickel plating process of the present invention. The nickel placed product comprises: a surface; a Ni—B layer which is electrolessly plated on the surface; and a Ni—P layer having substantially uniform thickness which is electrolessly plated on the entire surface of the Ni—B layer. Accordingly, a nickel plated product which has a Ni—B layer and a substantially uniform Ni—P layer electrolessly formed thereon can be obtained by using the nickel plating apparatus and/or process of the present invention.
REFERENCES:
patent: 4626479 (1986-12-01), Hosoi et al.
patent: 4745004 (1988-05-01), Schwerin
patent: 4964365 (1990-10-01), D'Amato
patent: 5711806 (1998-01-01), Harnden
patent: 0 475 567 (1992-03-01), None
patent: 0 762 814 (1997-03-01), None
patent: 8-281957 (1996-10-01), None
Harakawa Takashi
Nonaka Hideaki
Lamb Brenda A.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Toshiba TEC Kabushiki Kaisha
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